第7回オフラインリアルタイムどう書く（Java解答）

SelectChair.java

import static org.junit.Assert.assertEquals;
import java.util.ArrayList;
import java.util.List;
import org.junit.Test;

public class SelectChair {

    protected final char EMPTY = '-';

    public String solve(final String string) {
        String[] split = string.split(":");
        int chairNum = Integer.valueOf(split[0]);
        char[] chairs = initChairs(chairNum);

        char[] inOut = getInOut(split[1]);
        for (char each : inOut) {
            if (Character.isUpperCase(each)) {
                int recomended = searchChair(chairs);
                chairs[recomended] = each;
            } else {
                int awayIndex = awayChair(chairs, each);
                chairs[awayIndex] = EMPTY;
            }
        }
        String result = "";
        for (char each : chairs) {
            result += each;
        }
        return result;
    }

    protected char[] initChairs(final int chairNum) {
        char[] result = new char[chairNum];
        for (int i = 0; i < result.length; i++) {
            result[i] = EMPTY;
        }
        return result;
    }

    protected int searchChair(final char[] chairs) {
        List<Integer> primary = new ArrayList<>();
        List<Integer> secondary = new ArrayList<>();
        List<Integer> guttari = new ArrayList<>();

        for (int i = 0; i < chairs.length; i++) {
            char tmpChair = chairs[i];
            if (tmpChair == EMPTY) {
                if (chairs.length == 1) {
                    primary.add(i);
                } else if ((i == 0 && EMPTY == chairs[i + 1])
                        || (i == chairs.length - 1 && EMPTY == chairs[i - 1])) {
                    primary.add(i);
                } else if ((i == 0 && EMPTY != chairs[i + 1])
                        || (i == chairs.length - 1 && EMPTY != chairs[i - 1])) {
                    secondary.add(i);
                } else {
                    if (EMPTY == chairs[i + 1] && EMPTY == chairs[i - 1]) {
                        primary.add(i);
                    } else if (EMPTY == chairs[i + 1] || EMPTY == chairs[i - 1]) {
                        secondary.add(i);
                    }
                }
                guttari.add(i);
            }
        }

        int result = -1;
        if (0 < primary.size()) {
            result = getChair(primary);
        } else if (0 < secondary.size()) {
            result = getChair(secondary);
        } else if (0 < guttari.size()) {
            result = getChair(guttari);
        }
        return result;
    }

    protected int awayChair(final char[] chairs, final char c) {
        for (int i = 0; i < chairs.length; i++) {
            if (chairs[i] == Character.toUpperCase(c)) {
                return i;
            }
        }
        return -1;
    }

    protected int getChair(final List<Integer> chairs) {
        int min = chairs.get(0);
        for (Integer each : chairs) {
            if (each < min) {
                min = each;
            }
        }
        return min;
    }

    protected char[] getInOut(final String string) {
        char[] result = new char[string.length()];
        for (int i = 0; i < string.length(); i++) {
            result[i] = string.charAt(i);
        }
        return result;
    }

    @Test
    public void testSelectChairs() throws Exception {
        /* 1 */test("6:NABEbBZn", "-ZAB-E");
        /* 2 */test("1:A", "A");
        /* 3 */test("1:Aa", "-");
        /* 4 */test("2:AB", "AB");
        /* 5 */test("2:AaB", "B-");
        /* 6 */test("2:AZa", "-Z");
        /* 7 */test("2:AZz", "A-");
        /* 8 */test("3:ABC", "ACB");
        /* 9 */test("3:ABCa", "-CB");
        /* 10 */test("4:ABCD", "ADBC");
        /* 11 */test("4:ABCbBD", "ABDC");
        /* 12 */test("4:ABCDabcA", "-D-A");
        /* 13 */test("5:NEXUS", "NUESX");
        /* 14 */test("5:ZYQMyqY", "ZM-Y-");
        /* 15 */test("5:ABCDbdXYc", "AYX--");
        /* 16 */test("6:FUTSAL", "FAULTS");
        /* 17 */test("6:ABCDEbcBC", "AECB-D");
        /* 18 */test("7:FMTOWNS", "FWMNTSO");
        /* 19 */test("7:ABCDEFGabcdfXYZ", "YE-X-GZ");
        /* 20 */test("10:ABCDEFGHIJ", "AGBHCIDJEF");
    }

    protected void test(String in, String out) {
        SelectChair sc = new SelectChair();
        assertEquals(out, sc.solve(in));
    }
}